Hammer mill with decentric rotors



Aug. 14, 1951 H. c. POLLITZ 2,563,958

HAMMERMILL WITH DECENTRIC ROTORS Filed Nov. 9, 1946 s ShetsSheet 1 INVENTOR. HAROLD C. POLL/T2 Aug. 14, 1951 F'ild Nov. 9, 1946 H. C. POLLITZ HAMMERMILL WITH DECENTRIC ROTORS 3 Sheets-Sheet 2 //1// 1, /////IIII/1 INVENTOR. HAROLD C. POLLITZ.

75%3 6g Audra Aug. 14, 1951 H. c. POLLITZ 2,563,958

HAMMERMILL WITH DECENTRIC ROTORS Filed Nov. 9, 1946 3 Sheets-Sheet 5 'INVENTOR. HAROLD C. POLL/T2.

ATTYS Patented Aug. 14, 1951 HAMDIER MILL WITH DECENTRIC ROTORS Harold C. Pollitz, Cedar Rapids, Iowa, assignor to Iowa Manufacturing Company, Cedar Rapids, Iowa, a corporation 01' Iowa Application November 9, 1946, Serial No. 708,988

1 Claim. 1

This invention relates to a hammermill of the character commonly utilized to crush, pulverize, comminute, triturate, or bray solid materials, the invention being highly desirable for use in the crushing or comminuting of limestone and mineral products, although the invention will have other uses and purposes as will be apparent to one skilled in the art.

In the past, many and various types of hammermills have been developed, but were not as satisfactory as is desired by virtue of too rapid wear of the hammers. grates, linings, and other parts of the apparatus, replacement was exceptionally difiicult, and sudden injury of the type necessitating a shut-down was frequent if an uncrushable object accidentally entered the hammermill. Further, difficulty was sometimes experienced in clogging of the grates, undue wear of the lid lining, accumulation of material upon the breaker plate, and injury sometimes resulted when relatively large pieces of material bounded upwardly from the breaker plate. Perhaps the main objection to devices of this character heretofore known resided in the relatively small capacity of a given size of machine.

A feature of the invention is the provision of a hammermill including a curvate grate disposed adjacent the path of rotary hammer means, the grate and hammer means being so disposed relatively to each other that the space between the hammerhead circle and the grate progressively decreases in the direction of rotation of the hammer means, whereby added comminution of material results as the hammer means pass by the grate.

Still another feature oi the invention is the provision of a hammermill including an interior lining adjacent the path of rotary hammer means. and the lining and hammer means are so relatively disposed that the space between the hammerhead circle and the lining progressively increases in the direction of rotation of the hammer means. This construction provides a relief to lessen the likelihood of injury to the internal parts of the machine by way of an extra hard or uncrushed piece of material becoming wedged against the liner in front of a hammer.

Another object of the invention is the provision of a hammermill embodying a lining construction so arranged as to accumulate dust, dirt, comminuted material, and the like, and maintain that material upon its surface so that much of the wear resulting from the crushing or comminuting of material in the machine is taken up by such collection upon the lining, and thus the life of the lining is greatly prolonged,

Still another object of the invention resides in the provision of a hammermill having a curvate grate and a curvate lining disposed in succeeding order, with rotary hammer means forcing material against both, the disposition of the parts being such that the space between the hammerhead circle and the grate and the space between the hammerhead circle and the lining both progressively vary in the direction 01 rotation, but in opposite manner.

It is still a further object of this invention to provide a hammermill embodying a novel grate construction made up of spaced bars of even disposition at their inner edges, but of varying depths so as to vary the length of passages between adjacent bars and thus eliminate clogsing.

Still another feature of the invention resides in the provision of a hammermill embodying a breaker plate so disposed as to eliminate any danger of material bouncing upwardly from oil the breaker face, and so as to eliminate the accumulation of clay, powdered material, and the like from accumulating upon the breaker face and thus providing a cushion for material forcibly hurled against the breaker plate.

While some of the more salient features, characteristics and advantages of the instant invention have been above pointed out, others will become apparent from the following disclosures, taken in conjunction with the accompanying drawings, in which:

Figure lis a top plan view of a hammermill embodying the principles of the instant invention;

Figure 2 is an end elevation of the structure of Figure 1 taken from the right hand side thereof;

Figure 3 is an enlarged transverse vertical sectional view of the machine taken substantially as indicated by the line III--III of Figure 1, looking in the direction of the arrows; and

Figure 4 is an enlarged fragmentary central vertical sectional view, with parts shown in elevation, taken substantially as indicated by the line IV-IV of Figurel.

As shown on the drawings:

In the illustrated embodiment of the instant invention, there is shown a hammermill including a housing having a substantially rectangular base portion I, an upper wall portion 2 on one side, and another upper portion in the form of a lid 3 mounted to swing to open and closed positions on a pivot rod 4. With reference more particularly to Figure 3, it will be seen that in the top part of the wall 2, the housing is provided with a feed opening through which material to be acted upon is fed inside the hammermill.

In the bottom of the base I of the housing, a relatively large discharge opening 5 for comminuted or crushed material is provided. Preferably, suitable guide aprons l-l of curvate formation are provided along the sides of the base to guide material out the opening 6 and to prevent this material from accumulating in the corner portions of the housing.

Extending substantially centrally through the housing lengthwise thereof is a main shaft 9 carrying a suitable drive pulley ill on one end, and on the opposite end a balancing flywheel l I both of which are outside the housing. The shaft is preferably journaled in suitable bearings l2l2 also disposed outside the housing and carried upon suitable bracket supports l3l3. With reference to Figure 4, it will be seen that each bearing is preferably enclosed, the bearing proper being carried upon a pillow block I4 and having one or more lubricant openings l5 through which a suitable lubricant may be forced under pressure.

Inside the housing the shaft 9 carries rotary hammer means. These hammer means include a plurality of flat disks, l5. each of which is provided with an enlarged hub IE to adequately space the disks. The hubs iii are in abutting relationship all along the shaft inside the housing and are keyed to the shaft as indicated at H in Figure 3. Also as seen best in Figure 3, each of the disks is provided with a plurality of apertures l8 arranged. in the illustrated instance, in groups of three; that is, each three succeeding apertures are at different distances from the center of the shaft. Suitable hammer-holding pins l9 extend through the apertures, and in the illustrated instance. there are three such pin arrangements provided. 120 degrees apart. Each of the pins l9 passes freely through an aperture in each hammer. As seen clearly in Figure 4, a hammer comprises a shank 2| and a head 22, the outer face of the head being rounded as at 23 in Figure 3. The shank of each hammer is pivotally associated with the respective hammer pin l9, so that the hammer is free to pivot between adiacent disks upon the pins. The outer rounded face of the hammer eliminates undue wear upon the hammerheads. After a period of use, when the heads become naturally worn down to some extent, it is a simple expedient to place the pins l9 through the next outermost set of apertures and mount the hammers in position. thus compensating for hammer wear.

As the shaft 9 is rotated, the hammers are thrown outwardly into radially extending position by centrifugal force. The shaft 9 is preferably rotated at a relatively high speed so that the hammerheads, assuming they operate free. will define a hammerhead circle indicated by the dotted line 24 in Figure 3. Obviously, if a hammer strikes a lump of material to be crushed, the hammer may, if the pressure becomes too great. pivot backward from the direction of rotation of the shaft about its pin 2| and thus eliminate the danger of injury to the inner parts of the machine. As shown at 25 in Figure 4, the pins iii are preferably threadedly engaged in the end disk 15, and it is a very easy proposition to unscrew the pins, and remove the hammers for adjustment to a new position or replacemeht by new hammers.

With reference again to Figure 3, it will be seen that a breakerplate 26 is mounted in the wall portion 2 of the housing immediately. below one side of the feed opening 5. This breaker plate may be carried upon a pair of breaker plate studs 2|-21, and may be inwardly adjusted by means of a plurality of adjusting bolts 28 projecting through the housing. It will be noted that the breaker plate is preferably provided with a relatively smooth breaker face 29, although, if so desired, the face may be grooved. The breaker plate is positioned so that the face 29 is preferably upwardly and inwardly inclined, and the plate itself is disposed substantially in vertical position. With this arrangement, it is practically impossible for wet material, clay, powdered material, and the like, to accumulate on the face of the breaker plate and thus act as a cushion for material thrown against the plate. On the contrary, the breaker face 29 is kept clean at all times. There is another advantage in this positioning of the breaker plate, namely, that material hurled against the plate by the hammers 22 cannot bounce upwardly through the feed opening 5. The direction imparted to lumps of material entering the feed opening and being struck by the head 22 of a hammer against the breaker plate will have to be at an inward or downward angle. It should also be noted that the feed opening has inclined walls 30 which aid in directing incoming material toward the breaker plate.

Inside the housing, a crushing compartment that is substantially cylindrical with the exception of the feed opening 5 and the breaker plate 28 is defined by a curvate grate generally indicated by numeral 3i and a curvate lining for the lid 3 generally indicated by numeral 32. The lining and grate are positioned in successive order so that the lining in general forms a continuation of the curvature of the grate.-. As will later more fully appear, this is not an exact continuation of curvature, but only an approximate one.

At each end of the housing there is a substantially semi-circular grate support 33, the showing in Figure 4 being modified for purposes of clarity so that the rear part of this support and grate are omitted from that view. As is more apparent from Figure 3, the grate is made up of a plurality of spaced bars 34 interspaced with bars 35 of le s de th, all of the bars having a narrowed end portion to seat upon the respective grate supports 33 It will be noted that each grate bar 35 or 35 tapers; that is, the widest edge of the bar is inwardly, and the bar tapers radially outwardly to a narrow outside edge. This causes the space between adjacent bars to outwardly diverge and facilitate the discharge of crushed material through the bars. The discharge of such material is further facilitated by virtue of the alternate shallow and deep bar arrangement which shortens the passage between adjacent bars and leaves an enlarged passage as indicated at 38 through which the crushed material ultimately exists from the grate. All of the grate bars are evenly disposed at their inner edges, and the grate preferably extends throughout substantially a. full degrees. All crushed material must find its way from the crushing chamber through the grate, and as it leaves the grate it may fall through the discharge opening 6 in the housing, contacting either of the aprons I if expelled in that direction.

In order to permit cleaning of the grate, should such becime necessary, a clean-out (11101 31 is removably mounted in each end of the rousing.

The relative disposition of the grate and ham- .mer means adds to the capacity of the hammermill. As seen clearly in Figure 3, the grate is not concentric with the rotary hammer means. It will be especially noted that the space 38 between the hammerhead circle and the inner side of the grate varies in the direction of rotation. More particularly, this space progressively decreases in the direction of rotation of the hammer means from the initial wider clearance indicated at C to the narrow clearance indicated at C1 at the opposite end of the grate. Thus. diminution of a lump of material occurs as a hammerhead passes over the grate, and that lump of material may be further broken up against the edges of the grate bars by the hammerheads and forced through between the bars. It makes no difference whether the grate or the shaft 9 is actually slightly eccentrically disposed relatively to the other. It is only necessary that these parts be arran ed so as to provide a progressive variance in the space 38.

The lid lining 32 is preferably longitudinally grooved or corrugated to provide a series of channels 39 extending lengthwise of the lining. These channels after relatively short operation accumulate dirt and dust from the material being crushed and fill up to such an extent that thereafter much of the wear is taken up by that accumulation, thus prolonging the life of the lining itself There is an important feature of the relative disposition of the linin and the rotary hammer means. Here again, the respective parts are not arranged exactly concentrically, but the s ace 40 between the hammerhead circle and the lid lining also progressively varies. Preferably, this space varies oppositely to the s ace 38 between the hammerhead circle and the grate. namely, the space 40 progressively increases in the direction of rotation of the hammers from the narrow clearance adjacent the point C1 to the wider clearance at C2. This provides a relief between the hammers and lining which prevents wed ing of lumps of material between a hammerhead and the lid lining, and if that lump is too strong to be immediately broken, the relief permits an easy pivoting of the resnective hammer to release the lump tending to wedge, and the hammer may force that lump forwardly into sharp contact with the breaker plate 26.

In o eration. the instant invention is simple and. p itive. The shaft 9 is rotated by any suitable'drive means and the hammers will assume the position seen in Figure 3 by virtue of centrifu al fo ce. Then. material to be crushed is fed through the feed o ening 5 in the housing, and a this material falls, it is struck by the hammers and knocked against the breaker plate 26 to cause at least an initial fragmentation. The material is further comminuted as the hammers pass over the grate, and when it reaches a sufficiently fine degree of comminution as determined by the spacing between the grate bars, it is forced through the rate bars and exits through the machine. The forcing through of the material and the ultimate comminution of the material is greatly augmented by the progressive decrease in the space between the hammerhead circle and the grate. This adds materially to the capacity of the machine. Lumps of material which are not sumciently crushed in the first passto be forced between the grate bars are moved ahead in front of the hammers, and these lumps may be crushed to the desired degree in their passage over the lid lining, but it they are not so crushed, they cannot wedge in the lid lining by virtue of the progressive increase in the space between the hammerhead circle and the lid lining. Such lumps that may travel completely around the interior of the machine are forcefully propelled again against the breaker plate 26 and this keeps up until the lumps are broken up to the proper degree.

Should some uncrushable object enter the machine inadvertently, no damage of any real significance will result, the uncrushable object merely being propelled round and round by the hammers. When such an object is discovered, it may be removed from the machine through one of the clean-out doors 3! or through the opening provided by swinging back the lid. It. will be noted that lumps on traveling through the machine, especially the harder and more brittle lumps, will not follow an exact curvate path, but will bounce or ricochet on the breaker plate, grate, or lid lining, traveling in substantially a straight line between points of contact. After each bounce, the hammers will then catch these lumps in mid-air, and in some cases, the blow of the hammer is sufiicient to provide the necessary degree of further comminution. It should be noted in this regard that when a lump of material is knocked forcibly against the breaker plate 26 by a hammer, that lump cannot bounce upwardly but must leave the breaker plate in a direction below the point of contact, that is, in general downwardly where it may be again struck by an oncoming hammer.

From the foregoing, it is apparent that I have provided a hammermill that is quite simple in construction. and is constructed to increase the capacity of the mill proportional to its size, and provides a relief to prevent material being crushed from wedging in the crushing chamber and that safeguards surrounding objects in that material is prevented from rebounding out of the crushing chamber. Further, the machine is relatively simple in construction, all. parts are easily accessible, and the entire machine is very economical to manufacture and operate through an extremely long life.

It will, of course, be understood that variou: details of construction may be varied through i wide range without departing from the principle: of this invention and it is, therefore, not the purpose to limit the patent granted thereon otherwise than necessitated by the scope of the appended claim.

I claim as my invention:

In a hammermill, a housing having a feer opening in the top and a discharge opening a the lower level, a curvate grate in said housing below said feed opening, rotary hammer means inside said grate positioned to comminute material against said grate, a breaker plate disposed above an end of said grate and below and mainly to one side of said feed opening, said breaker plate presenting a substantially flat inside face upwardly and inwardly inclined, said grate comprising spaced bars evenly disposed on the inside edges but of varying depths, a part of said housing being in the form of a lid, a curvate lining in said lid, and said grate and said lining being arcua-te and oriented with respect to said hammer means to provide a gradually narrowing space between the hammerhead circle and the grate and a gradually widening space between the hammerhead circle and the lining in that order and in the direction of rotation.

. HARD LD C. POILITZ.

REFERENCES CITED The following references are of record 111' the file of this patent:

UNITED STATES PATENTS Number Name Date Douglas et a1 Oct. 24, 1876 Albrecht May 17, 1898 Sturtevant et al. Jan. 18, 1900 Shelton Feb. 3, 1914 Liggett Jan. 19, 1915 Thompson Mar. 16, 1915 App Feb. 1, 1916 Blankmann June 26, 1917 Shelton Apr. 29, 1919 Number Number 

